This study will compare 2 different sedation drugs (Ketamine and Midazolam) when they are
used with another sedating medicine called Dexmedetomidine for MRI sedation. This study
hopes to measure the impact each drug has on what happens during and after MRI sedation with
The will be a randomized, double-blind, prospective study. All patients referred to UCSS for
brain MRI and for whom dexmedetomidine would otherwise be the sedation regimen of choice
will be eligible for enrollment. The investigators propose to limit the study to patients
undergoing only brain MRI as these studies are of a predictable length (25-30 minutes);
therefore the sedation regimen can be more easily standardized. Parents of eligible patients
would be approached prior to or during the pre-sedation assessment and told about the study
and, if they agree to enroll, informed consent would be obtained. Assent will be obtained
from children 7 years of age and greater, if they are otherwise developmentally capable of
giving assent. The goal is to enroll 50 subjects (25 per treatment group) which would be
sufficient to detect a 25% or greater difference in the mean maximal heart rate or blood
pressure decrease from baseline between the 2 groups.
Following consent, subjects would be randomized to be sedated with either
midazolam-dexmedetomidine or ketamine-dexmedetomidine and, upon achieving an appropriate
depth of sedation, undergo their MRI. Monitoring during the MRI and subsequent recovery
would occur in compliance with the current Norton Children's Hospital Sedation policy.
Recovery-related behavior would be assessed using the Pediatric Anesthesia Emergence
1. Inpatient at Kosair Children's Hospital.
2. Order placed by treating team for MRI of the brain with sedation.
3. Age less than or equal to 18 years.
4. Plan to sedate with dexmedetomidine, regardless of study participation.
1. Previous adverse reaction to dexmedetomidine or clonidine
2. Current use of clonidine as a routine medication
3. Concurrent use of a heart-rate decreasing medication (digoxin, propranolol)
4. Contraindication to ketamine use
- Intracranial hypertension or traumatic brain injury
- Intraocular hypertension of eye trauma
- Pulmonary hypertension requiring medical management
5. Planned additional procedure during the sedation encounter (non-brain MRI, lumbar
puncture, EEG etc)